1. Field of the Invention
The present invention relates to antistatic resin compositions having an excellent permanent antistatic property and adapted for use in injection molding for preparing moldings having an improved surface appearance.
2. Description of the Prior Art
ABS graft copolymers have excellent mechanical characteristics and are therefore used in a wide variety of fields, whereas these copolymers are not antistatic and have accordingly found limited application to office automation devices and dustproof uses wherein troubles due to static electricity are to be precluded.
Antistatic properties are imparted to ABS graft copolymers, for example, by coating the surface of the resin with surfactants or the like or by incorporating surfactants into the resin by kneading, but these methods still remain to be improved in the durability of antistatic effect. Articles of such resin become impaired in the durability especially when washed with water.
To overcome this drawback, it has been proposed to admix an epihalohydrin copolymer with the graft copolymer (U.S. Pat. Nos. 4,588,773, 4,719,263 and 4,775,716), to admix an ethylene oxide copolymer with the graft copolymer (E.P. No. 287,092A2), to add an acrylate polymer to the graft copolymer as a third component (E.P. No. 294,722A2) and to add a specific modified vinyl polymer to the graft copolymer (Unexamined Japanese Patent Publication No. 269147/1990). Although affording improved permanent antistatic properties, these methods are found to have the problem that the product obtained by injection molding has faults in the appearance of its surface, such as weld lines and pearl gloss. This problem reduces the commercial value of ABS resins which are generally used for the housings of office automation devices and household electric devices, interior finishing materials, etc. of which an esthetic appearance is required and which are often produced by injection molding, consequently limiting the use of the resin.
The main object of the present invention is to provide antistatic resin compositions for injection molding which comprise as their base an ABS resin giving an excellent surface appearance.